This invention relates generally to coupling assemblies, and, more particularly, to methods and apparatus for coupling gas turbine engine components together.
At least some known mechanical coupling assemblies used to couple gas turbine components together include a threaded fastener and a threaded connector. More specifically, within at least some known applications, the threaded fastener is inserted through an opening formed in a flange prior to a connector being threadably coupled to it for securing a component to the flange. At least some known flange openings are counter-bored to enable a portion of the threaded fastener to remain recessed with respect to an external surface of the flange after the fastener is coupled to the flange.
As the connector is threadably tightened to the fastener, clamping loading is induced to the flange. However, when counter-bored openings are used, at least a portion of the clamp loading induced to the flange is carried by the thinner portions of the flange that define the counter-bore. Over time, the uneven load pattern stresses induced within the flange may cause the edges of the fastener opening within the flange to roll inward and away from the threaded connector, in a condition known as “bolthole rolling.” Bolthole rolling may cause additional stresses to be induced to the flange which over time may cause a premature failure of the flange.